I'm trying to convert a one-to-many relationship in entity framework to a many-to-many.
I've done the admin work and generated a database, which seems to be fine but now I'm running through the resulting errors and trying to get the code to compile. Most of it is fine, but one particular change is giving me a headache - I can't figure out the correct syntax. I'm sure I'm being very stupid here.
The original line was:
addedService.CompiledDatabase = context.Databases.OfType<CompiledDatabase>().First();
But addedService.CompiledDatabase is no longer looking for a single instance of CompiledDatabase, it's looking for a collection: an EntityCollection to be precise.
I can't figure out how to get a linq/lambda query that will return a collection of the required type. Assistance gratefully appreciated.
Something like?
addedService.CompiledDatabase.Attach(context.Databases.OfType<CompiledDatabase>());
...if addedService is already in context.
Related
I'm trying to create a chat bot that will help users search up motorcycles.
I'm new to API.AI and have set up my entities and their synonyms, my intent and user expressions, as well as references to the entities (#engineSize, #make, #bikeType).
My problem is when I try to add a required action and prompt, and then try to save the intent, I get the following message:
"The following entities reference each other and form an infinite loop: [engineSize]."
Initially I thought I was using the references wrong in the user expressions. I deleted every reference except for one expression which uses all three entities.
I can't figure out what I'm doing wrong. Any help would be greatly appreciated, thanks! Pix below for further details.
EDIT: I fixed one of the issues of trying to pass a template expression as an example. However, I still get the same error message. I will replace and update my image links to include the edits.
Annotated User expressions
Required Actions
Interestingly enough, the answer to this post would have been difficult to find because the problem was in defining my entities.
In the entity definitions, I included an #ref to the entity itself. ie the bikeType entity contained #bikeType as one of its definitions.
This is not to be mistaken with the User Expressions. As long as the user expression is marked as a Template (the entire line is denoted with an '#' on the far left, as opposed to a large " ), there should be no issues.
Edited for clarity to get at root problem
In the provided user input examples you give the intent, you are supposed to provide general examples and then highlight any text belonging to an entity to map where entities appear in user's inquiries.
In your case, you have input the actual entity reference '#engineSize' as an example belonging to the engineSize entity, creating a self reference.
A proper provided user example would look like:
Also note though that if you are just using entities to store generic information like numbers, addresses, times, etc. it generally makes far more sense to use prebuilt system entities for those categories than create a custom entity, for example #sys.number-integer might be exactly what you need
It looks like you need to get a firmer understanding of entities, for which I would recommend the documentation:
https://docs.api.ai/docs/concept-entities
I am working in VS 2015 solution with an MVC 5 project and a code library project using EF 6.1. I have redone the entire project from a previous version in VS 2013 hoping it would resolve this problem, but no luck. I am just trying to eager load a child with grandchildren. I tried this:
Test t = db.Tests
.Include("TestsRemoteOBD")
.Include("TestsRemoteOBD.TestsRemoteOBDDtcs")
.FirstOrDefault();
and this:
Test t = db.Tests
.Include(i=>i.TestsRemoteOBD)
.Include(i=>i.TestsRemoteOBD.Select(s=>s.TestsRemoteOBDDtcs))
.FirstOrDefault();
Include using the string works for the child, but not the grandchildren. And with the 2nd query, I'm getting this error:
'TestsRemoteOBD' does not contain a definition for 'Select' and no extension method 'Select' accepting a first argument of type 'TestsRemoteOBD' could be found (are you missing a using directive or an assembly reference?)
I've seen the same question resolved by adding "using System.Data.Entity;", but I had done that a long time ago. No help. What else could I be missing?
Thanks!
Thanks so much, to all those who commented. I would have been banging my head for another day, at least. The way I had written the second statement would have worked fine if the parent [Tests] had a 1-to-many relationship with [TestRemoteOBD], but since the latter was not a collection, there was no 'Select' defined. I have not tested, but I believe it should be something like:
Test t = db.Tests
.Include(i=>i.TestsRemoteOBD)
.Include(i=>i.TestsRemoteOBD.TestsRemoteOBDDtcs)
.FirstOrDefault();
Bump. Found this and thought I'd throw in my own research.
Microsoft's
Documentation
states: To include a reference and then a reference one level down: query.Include(e => e.Level1Reference.Level2Reference)
-- but this doesn't seem to work under even the simplest use case. Executing the query with a .ToList() does not actually include anything. Smells like an obvious bug to me!
I can see 2 workarounds.
First, as Ben here suggests, you can manually iterate over the entities to force EF to load them.
Second, if scoping permits, you can forget the 'using' block and keep a more permanent instance of the dbcontext as a class member so that it's still available, not disposed (System.ObjectDisposedException), when the members are accessed.
I'm learning from breeze-zza-mongodb sample.
I get some problems when i try to use the saveChanges() function from breeze.
This is the error i get:
"TypeError: Cannot read property 'update' of null at... node_modules\breeze-mongodb\mongoSaveHandler.js : 229:20 at Array.forEach"
Any of you tried and got this error? I searched Google for a bit longer but i can't find this issue. And if i try to manager.getChanges() and put the changes in array, i get my entity with modified state.
The guys from breeze didn't covered this part and i'm completly blind in this. Thank you for your time guys.
I solved my problem. I included the modules in VS so i can debug and i noticed that breeze misnamed my collection name for some reason adding an s at the end.
Anyway.. for now i just removed that, and it works. I will dig deeper to see where and why is breeze adding an s at the end of my collection name because i want to treat the cause, not the effect. Thanks.
(I am also using .NET 4.0 and VS 2010.)
I created a function import returning a complex type, as explained at http://msdn.microsoft.com/en-us/library/bb896231.aspx. The function import and new complex type appear in my .edmx file and in the Designer.cs file. However, the function does not appear when I view the service in the browser, and when I add or update a service reference in the client project, the function does not appear there either - as is to be expected, given the first result.
Creating an imported function and using it seems conceptually very simple and straightforward, and one would think it would just work, as Microsoft's step-by-step instructions appear to suggest: http://msdn.microsoft.com/en-us/library/cc716672.aspx#Y798 (which article shows the SP returning entity types - I tried this also, and it doesn't work for me either).
This blog post shows the addition of a method to the DataService class, which Microsoft's instructions omit: http://www.codegain.com/articles/wcf/miscellaneous/how-to-use-stored-procedure-in-wcf-data-service.aspx I tried adding one method returning a list of entity types and another returning a list of complex types, and still had no success. I still could not access the functions, either directly via the browser or from the client application via a service reference.
Thanks in advance for any help with this.
config.SetServiceOperationAccessRule("*", ServiceOperationRights.All);
MS would do well to add a note to the walkthroughs stating that the above bit of code must be there. (It may be better to enable each operation explicitly than to use "*".)
http://www.codegain.com/articles/wcf/miscellaneous/how-to-use-stored-procedure-in-wcf-data-service.aspx shows that line of code. Also, something it is there in the code, commented out, when one creates the WCF Data Service. Some of us like to delete commented-out code that we aren't using and that seems irrelevant - perhaps doing so a bit prematurely, sometimes.
I have a fairly simple question to which I cannot seem to find the answer for. I have a silverlight app with Ria Services. In the DomainService class I have an update method like below:
public void UpdateConversationState(ConversationState currentConversationState)
{
var original = ChangeSet.GetOriginal(currentConversationState);
if (original != null)
ObjectContext.ConversationStatesRepository.AttachAsModified(currentConversationState, original);
else
ObjectContext.ConversationStatesRepository.Attach(currentConversationState);
currentConversationState.UpdDat = DateTime.Now;
if(original.Name != currentConversationState.Name)
//Do something extra
}
The problem is that the Name property is always empty. In fact every field except for the Id has default values. I've tried searching for how the GetOriginal method works, but cannot find any help. It seems to mee like it tries to rebuild the original object on the server, based on the changes that are sent back from client to server.
Or maybe anyone knows a better way to check if a certain property of an object has been changed during an update? I could off course compare it to the value in the database, but it seems like I should avoid this extra call to the database.
Any help is again much appreciated :-)
EDIT:
Just found out about the RoundTripOriginalAttribute. This seems to do the trick. Am I the only one by the way that think RIA could be documented a little bit better?
Well, I've been also looking for a way track entity changes with EF4 and after some googling I've found that you need to apply the "RoundTripOriginal" attribute to the properties of the entity you want to track, because RIA (by default) does not send the original values back to the server.
I still have some concerns on this and I asked some of the gurus:
http://forums.silverlight.net/forums/t/218332.aspx
This worked for me, but I still don´t think is the best way out of it.
Hope this helps.